Vendée Globe: The Difficult Route Through The South Atlantic

Vendée Globe: The Difficult Route Through The South Atlantic
Vendée Globe: The Difficult Route Through The South Atlantic

Video: Vendée Globe: The Difficult Route Through The South Atlantic

Video: Vendée Globe: The Difficult Route Through The South Atlantic
Video: Vendée Globe - sailing in violent storm with 50 knots - Sturmsegeln im Southern Ocean 2024, March
Anonim

As every weekend, the British professional skipper analyzes the weather and racing events for the coming days. He finished his studies late on Saturday evening, when nothing was known about the structural problems on board Alex Thomson's "Hugo Boss", which changed the ranking at the top overnight.

Thomson is currently sailing at a greatly reduced speed so as not to endanger his boat, but stayed on course for the time being. We will report on it in detail as soon as there is news from his team on the exact severity of the damage and its possible cause.

Here Will Harris' outlook on possible routes to the Cape of Good Hope and why the South Atlantic will be trickier than at the previous Vendée Globe four years ago:

The leading skippers could not have wished for a better passage through the Kalmen last week. Hardly anyone was slowed down or suffered massive losses because they were stuck on the wrong side of a cloud - as is so typical for the zone north of the equator.

For the following group of boats, things look a little different at the moment. Pip Hare on "Medallia" and Arnaud Boissieres on "LMie Caline", who are currently crossing the calm zone, have to deal with a minefield of calm zones. For them, the Doldrums are extremely difficult.

Far in the South Atlantic, on the other hand, the leaders had several days to ponder their various options for getting to the Cape of Good Hope, some 2,400 nautical miles to the southeast.

It was far from clear which way to go. Normally you would hope that the ensemble routings show a clear "path". The South Atlantic looks quite complicated in the next few days, however, as the Sankt Helena high shifts westward and leaves behind several light wind zones.

First, let's look at the details of the leadership trio. We saw how Alex Thompson left the Doldrums on "Hugo Boss" with a considerable lead of 100 nautical miles on "Apivia" and "LinkedOut". Alex then opted for a more westerly route than the other two and steadily lost miles to both.

An interesting tactical question is why didn't he just position himself between his competitors and the "route" to the Cape of Good Hope? Maybe it was because he thought the way west was a little faster. It could also be because Alex assumed his boat would be faster with the resulting wind angle, and sailing the extra distance would pay off. Obviously that was not the case. Instead, it was possible to observe how quickly such a lead can fade.

The South Atlantic has some characteristics that are special: Dist on the one hand the Sankt-Helena-Hoch. This drives the trade winds of the South Atlantic, but it is also very important for the strategy towards the Cape of Good Hope. The position of this high pressure zone can change rapidly as it interacts with the other weather systems in the area. Hence, there needs to be a good understanding of what state the high is in before considering a course to the Cape.

Another feature is the South Atlantic Convergence Zone (SACZ). This is basically the meeting point between warm air from the north and cold air from the south, which begins along the Brazilian coast and extends southeast into the South Atlantic. It creates ideal conditions for cyclogenesis, and low-pressure systems regularly form along this zone of convergence.

Vendée Globe tactic for the South Atlantic
Vendée Globe tactic for the South Atlantic

Figure 1: Pressure distribution and wind in the South Atlantic. The low L1 in the west will slowly move to the east and rise in the Sankt-Helena-Hoch. The leading boats (red circle) try to latch into the deep and make the most of the fast headwind

Both of these features will be relevant to the leading skipper's strategy over the next few days. A low (L1) has formed along the SACZ and is moving to the southeast. The Sankt-Helena-Hoch in the northeast and a larger low pressure area (L2) in the south forces everything to convergence. On Monday morning, L1 is absorbed and disappears; it leaves a large area of light wind on the direct route to the Cape of Good Hope. When L1 disappears, there will also be a clear track for the Sankt-Helena-Hoch, which changes to the southwest.

What does this mean for routing?

At first, sailing towards L1 appears to be the best option as it offers fast headwind conditions. The complication is that there is little wind left after the lows clear. The only option is to find a route south. Those further ahead, like Apivia and LinkedOut, will do better with this strategy because they are closer to L1 and can make the most of the good wind before it disappears. However, you also have to be prepared for numerous exhausting maneuvers because the wind corridor is quite narrow.

Vendée Globe tactic for the South Atlantic
Vendée Globe tactic for the South Atlantic

Figure 2: Air pressure and wind on Monday 2200 UTC. Low L1 is flattening out and will be gone by Tuesday morning. L2 in the south moves rapidly to the west and compresses the Sankt-Helena-Hoch in the north. As soon as L2 moves away, the high will shift to the west

The other option is to sail further south for the time being and effectively try to sail west of Saint Helena High and L1. This route means covering a lot more distance, and initially with quite light winds. But later, once you are far enough south, fast spacer conditions prevail up to the Cape of Good Hope.

Those farther back will do better with this strategy, as the high of Saint Helen will have had more time by then to establish itself in the west and then slowly move back east, making the route shorter.

Vendée Globe Strategy for the South Atlantic
Vendée Globe Strategy for the South Atlantic

Figure 3: This is what the possible routings look like. The red course line is the direct route preferred by the leaders, the blue is the southern and longer option for sailing west of high pressure

Judging by the courses in the top 10 of the fleet, the fastest skippers yet consider the western option too risky because it requires so much additional distance. However, there is still a chance to come loose. Perhaps we'll see some gamble.

Right now it's great to watch the battles for position at the very front - a study of the Imoc60's performance differences on the cutting edge of design. As the fleet approaches the Southern Ocean, we will get a better idea of how these structures work under the extreme conditions and who is ahead of the curve."

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